Dkkws



C. W. ANDREWS. A

FLOUR MILLING PROCESS. APPLlcAlou nl gn M1648, sus.

1,381,266- Patented June 14, 1921.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

NEW YORK, ASSIGNOR TO CARRIER OF NEW YORK, N. Y.

FLOUR-MILLING lPROGESS.

Specification of Letters Patent.

Patented June 14, 1921.

Application led August 28, 1916. Serial No. 117,154.

To all whom if may rohre/In.'

lie it known that l. (filantes ll'nns'rsu N- Dnnu's, a eitizen oi' the United States. residing at Buffalo, in the county of Eris and State of New York. have invented a new and useful Improvement in Flour-Milling Processes, of which the folliinving is a speeifieation.

This invention relates to flour milling proeesses and has for its objet-ts to make the milling prouesses indelnudent ol the eeet of variations in atmosplierie conditions, whirh ell'eet is partieularly noticeable and objectionable ou hot, humid days; to make the flour separate more readily from the bran; and hv controlling the condition ot the storlt in the milling prot-ess to materially increase the yield and the quality of high Igrade flour.

ln the milling of flour the stock becomes heated in the grinding rolls to a materially higher temperature than ordinal-il)7 prevails in the spoutsconveyors and separating nulehines` through whirl the stock passes from the rolls` so that elianges of temperature in the sterk and changes in the vapor pressure ol' they atmosphere in eontaet with the stoel( oerur whirh interfere seriously with the proper millinpA ot the stoel( and lessen the `vield of high grade flour, For instaure1 the heat may drv the stoel; enough to leave the lu'an so brittle that it is timely ground up with the flour and (-annot he readily separated therefrom, and the temperature of the stoel( heinrt;` hi flier than that of the air and the chutes anillother apparatus with which the stoel( eomes into eontaet, causes the rolls. holters, spouts, ete., to sweat and moisten the stoel: so that it pastos up the holtinpr sillts and interferes with the separat.- ing process. (`onditions are mufh less 'favorable to lfood yields in summer than in winter lieeause temperatures and humidities are higher in summer and lessen the cooling rll'erl of the present suction systems on the rollsy and other apparatus.

lt is recognized that there is a elose rela tionship between the atnmsplwrnI eonditions within the mill and the perrentage of high grade flour yield. and after rarefnl observations, comparisons and experiim'ints` extendingr over a eonsideralole period of time, l have determined that yields of high grade our can he obtained eonsiderahly in excess of the yields heretofore obtained under the most favorable milling eonditions by Cooling the heated flour stocks, Jreparatory to the separating proeesses in the bolters, reels, etre., to the temperatures liest conformable to the separating processes. The loes` resuits are secured by maintaining suitable atmospheric renditions within the mill` particularly in the room containing the grinding rolls` where a lgreat deal of heat i': cleveloped, in addition to directly cooling,r the stocks before they reach the separating apparatus, so that the vapor pressure of the moisture of the stocks will be less than the vapor` pressure correspondingr to the temperature of the atmosphere (and incidentally of the apparatus) with which the stocks come into Contact after leaving the rolls, and also where necessary, increasing the moisture content of the stocks after leaving the separating apparatus and before the subsequent reduction thereof. y

It may be said`r in explanation of the foregoing, that a certain relationship exists between the temperature and moisture content of hydroscopie materials, among which flour may he classed, and the temperature und relative humidity of the atmosphere sur rounding the material. It is usua in speaking srientiteally ot' this relationship to use the terms vapor pressure of the moisture in the, material and vapor iressure of the water vapor in the air. l hen these two vapor pressures are equal, for all practical purposes, it may be said that the processes of absorption and evaporation cease, and a definite constant relationship between the moisture content of the material and the relative humidity of the atmosphere results. The vaior pressure of the, n'ioisture in the material depends both upon the percentage of moisture which it contains and the temperature of the material. That is, the vapor pressure increases both with the moisture content: ot' the material and also with the temperature oi' the material. For example, material with a relatively low moisture content hut at high temperature will have its vapor pressure increased above that of the surrounding air so that it will give olf moisture even in air that is nearly saturated. It may thus he understood that by reducing the vapor pressure of the moisture in the material by lowering the temperature of the material itself, that the tendency of the material to give olf moisture to the surrounding atmosphere is greatly reduced. ln this wise. the condensation which occurs in the spouts. conveyers, holters. reels. ete.. and which is so ob]ectionable, can be entirelyY prevented by keeping the vapor pressure of the atmosphere 1n immediate eontaet with the niav terial in its passage through the aforenieutioned apparatus rom ever reaching a point that is greater than the vapor pressure corresponding to the tenilnrature of the at mosphere that is in contact with the outside of these spouts, conveyers, bolters, reels, etc.

The stocks. can be eoled in various wa vs. as, for instance by passing a. cooling inediluu through the hollow grinding rolls, but pref-4 erably the cooling is effected bv causing the Stocks leaving the rolls to be evenly dis tributed in thin streams or curtains through which are passed currents of air which have been Saturated or substantially saturated with moisture at :L suitable temperature. usually between to (S0 F.. and regulating the volume of air supplied so as to secure the required reduction in temperature of the stocks. By using saturated ai at the proper temperature, the necessary cooling of the stock is effected under ordinary eonditions with but a. very slight reduction in the moisture content of the stock. This SlightI` loss in moisture can be again supplied to the stocks between the separating apparatus and subsequent grinding rolle. The air is saturated, not for uioistening the stock but for cooling it without unduly reducing its moisture content. While the use Of air saturated at a predeterinined teinperatuie insures eertaintv and uniforinitiI of results, and is therefore preferably ein ployed, less perfect, but good results can be secured by the use of luunidified air which is not fully saturated.

The apparatus preferably employed in carrying on the process is constructed as follows In the accompanying drawings:-

lfigure 1 is a diagrammatic sectional view of the apparatus.

Figs. 2 and 3 are respeetively a cross seetion and a longitudinal section of the stoel; conditioning device.

Figs. 4 and 5 are iespectively a. longitudinal and a cross section of the stock moist/suing device.

l A .\J represent two sets of grinding rolls and B a separating apparatus, which niav be the bolter, reel` purifier or other sepa-ratingI alpparatus' through \\'hiehlthe stocltpaeses from one set of rolls A and from which the unfinished stock passes to the other set of rolls A. @he rolls A may be either for the first, break or for a Subsequent reduction of the stmk while, the rolls it may he the rolle v for the second or any subsequent griinlingF of the unfinished stock from the separating C represents an elevator for delivering the stoel( from the rolls A to toe separating apparatus. All of these devices are parte of the usual flour mill and may be of any suitable construction and arrangenient.

l) represents' a `stock conditioning or oooh ing device through which thc stock passes on its way from the rolls A to the separating appar-.Itas l): and in which the stock is subies-teil to the cooling action of the humiditied air. and ll represents a lnoistening device. located between the separating appa ratus and the second grinding rolls A', in which the moisture content, of stock may be increased preparato@Y to further reduction by the rolle- A'. As: Shown in the` drawings, the stoel; is delivered from the rolls to the conditioning device i) through a chute Il and passes from the ein `,itioniug' device. through a chute rl to the eievatm'` while the unfinished stock is deliverml from the :separating apparatus to the nioisteuing device E and from the latter to the reduction rolle A' by chutes c and f" respectively.

The conditioner or cooling device D pref` erablv comprises a box or chamber provided at itsy upper portion with a screw conveyer l and adjustable gates L. or other means whereby the stock from the rolls is evenly distributed throughout the width of the chamber and caused ro fall through the chamber in a thin sheet or curtain, and provided al its lower portion with a srrevv con\e ver or other suitable device 3 for discharging the stock from the conditioning chanilwr. n air suppiir duet. l ie. arranged in the louer portion of the CondiA tiouing chamber. the duct having a perforated wall fr and being tapered to evenly distribute the air throughout the length of th conditioning ehamber.y and an exhaust duet also preferably taperclh is located in the upper portion of the chamber. The stoel( in falling through the, conditioning chamber strikes oppositelv inclined baffles or plates i which are separated by spaces through which the air can pass from the suppl)v duet to the exhaust duet through the falling stoelt. than: insuring an intimate and thorough contact ol the air with the stock.. The air supply duet is provided with a damper h to regulate the volume of air supplied lo the eonditioning ehaniliei' and the exhaust duet is :den preferably provided with :i damper il intox-conuci-ted with the suppl)Y damper in such a way as to regulate the exhaust in zu'coril:inrf, with the Supply, L c.. ee,- that practically the saine quantity of air is', exlmuated from the eonditioner as is aupplied thereto. .i ramditioner or cooling device oi' anir other suitable construetiou which will insure'a thorough and uniform distribution of the air in proper volume through the Stock could he emapparatus.

lOl?

iSQ

ployed, but the construction above described is efiicient and desirable for the purpose.

The air supplied to the conditioner or cooling d ice preferably has a suitable predetermine dew point or is saturated with moisture at a predetermined temperature so as to have a definite moisture con tent. This can be accomplished by any suitable air refrigerating or-conditiouing a paratus. In the apparatus indicated at in the drawings for this purpose, which is of known construction, the air 1s drawn through cold water sprays in a cooling chamber l() by a fan ll, the temperature of the chamber being controlled by regulating the temperature of the spray water and properly proportioning the almounts of fresh air and return air from the mill enteringr the cooling chamber, or otherwise, under the control of a thermostat l2, which iS affected by the temperatur@` of the saturated air, so that the air is saturated at a definite temperature, depending,r upon the adjustment of the apparatus. A refrigerating coil 13 is shown forcooling the spray water which cools the air. Means can also be provided for raising the temperature of 4the air, it this becomes necessary in cold weather. In the ordinary operation of the process the absolute humid ity of the air entering the refrigeating apparatus F is such that when the air is cooled it is dehumiditied and leaves the apparatus substantially saturated at the temperature for which the apparatus is adjusted, which is ordinarily between and 60 F. While the air refrigerating or debumidifying apparatus shown is of the spray type 1n y which the air is cooled by Contact with cold water sprays, any other suitable type of refrigerating;r or dehumidifying apparatus vcould be employed, such, for example, as the Well known condenser coil type in which the air isfcooledby contact with the coils of ipe through which a cooling medium circuates.

The air thus saturated at the required predetermined temperature is delivered by the fan 11 through a discharge conduit 14 to the stock conditioner D. The volume of the saturated air delivered to the stock conditioner canbe regulated with reference to the temperature and quantity of the stock so as to secure the required cooling of the stock by adjustingY the controlling dempers 8 and 9 by hand, but the regulation is preferably perfo med automatically as by means of a therm at 15 which is located in the stock conditioning chamber and is affected by the temperature of the stock or of the air lafter it has' passed through tbe stock. This thermostat preferably controls the flow of compressed air through a pipe 16 to a diaphragm or motor 17 for actuating the air supply und exhaust dempers 8 and 9, A thermostat of any usual or suitable construction can be cmployed and it can operate the dempers through any suitable instrumentalities.

As shown` the air exhaust duct of the stock conditioner l) is connected by apipe 18 with a dust collector (i for SparatinpY from the air anv dust or stock therein, and the air may be discharged from thisl dust collector into tbe mill for cooling?r the latter and returned to the air conditioning device l" to be again conditioned and' returned properly saturated and tempered to the stock conditioner l).

The volume of the conditioned air with reference to the temperature o f the stock is so controlled either by hand or automatically as described, that the stock flowing from the rolls A will be sufficiently cooled so that-thc vapor pressure of the moisture in thestock always will be lessthan the vapor pressure corresponding` to the temperature of the atmosphere orthe pparatus with which the stoc subsequently comes into contact.v The chutes, elevators and separatingr apparatus, therefore, will not sweat and cause the condensation of moisture on the stock and the stock Willrpass to the separating: apparatus in the condition most suitable for separation. (lne of the stock conditionersl l) can be provided for cooling the stock, leaving any one or more of the sets of grinding rolls in the mill as may bc found necessary, and the supply of saturated air to each conditioner will be independently controlled as above indicated in accordance with the temperature of the stock beiner treated in this conditioner.

Any suitable means can be used to produce the desired moisture content in the stock. The moistcningr device E shown comprises an inclined rotary drum into which the stock is delivered at one end and which is provided intcriorly `with suitable oblique flights 20 adapted to carry the stock up and let it fall through the chamber ofthe drum to be moistened by a very finely atomized water spray-or steam from a suitable de vice or atomizer 21. rlhe moisteniing of the stock can be suit-ably controlled by proper regulation of the water and compressed air supply of the atomizcr. instead of usine;v atomized water, steam can be use( with cool saturated air, which produces a ne fog or mist free from drops and will therefore insure u very accurate, uniform nloistening of the stock. The moistened stock passes from the nioistcning device ld to the grindingr rolls A. As thc stock is not'moistened until utter it lcavcs the separating apparatus1 the separating,r operation is not impeded or all'ected in any manner by the added moisture in the stock.

H represents an air conditioningr apparatus for supplying air to the I(grinding room' purilicrs and reels or other parts of the mill suitably conditioned with reference to humidity and temperature o'r maintaining the most suitable atmospheric conditions in the several parts of the mill. This apparatus can be simi-lar to the air conditioning apparatus F or of any other suitable construe` tion. One apparaliqs H is shown 'for sup' plying air to several of the mill rooms, but one or more air conditioners will be employed, depending upon the size of the mill and the atmospheric conditions prevailing therein. The atmospheric conditions in the several' parts of the mill can be maintained as required by any known or suitable means, it heilig understood that the conditions are regulated so as to co Yerate to the best advantage with the stoclconditioning means in maintaining the stock at the conditions of temperature and moisture best suited to the operations to be performed on the stock. As shown, the air supply pipe 22 for eac'h room is equipped with a heater 23 under the control of a. hygrostat 24 in the room.

These hygrostats can be set so as to maintain the required atmospheric conditions in thc several rooms.

I claim as my invention 1. The herein described process of milling flour, which consists in grindin the stock, cooling the ground stock by su 'ectr ing the same to the action of humidifie air having a temperature lower than the temperature of the room, and regulating the Volume of the humidified air under the control of the temperature of the stock to cool the stock to a, predetermined temperature.

2. The herein described process of milling Hour which consists in grindinv the stock,

. cooling the ground stock by su jecting the same to the action of the alr which is satu- Same to the action of humidified rated with moisture at a definite 'temperature, and regulating the volume of the saturated air under the control of the temperatureo'f the stock to cool the stock to-a predetermined temperature.

3. The herein described'process of milling flour which consists in grindin the stock, cooling the ground stock by sujecting the air having a temperature lower than the temperature of the room, and automatically' regulating the volume of the humidified air to cool the stock to a predetermined temperature.

4. The herein described process of milling 'lour which consists in grindin the stock, cooling the ground stock by su jecting the same -to the action of humidied air having 'a temperature lower than the temperature of the room, regulating the volume o'f the humidied air under the controlof the temi perature of the stock to cool the lstock to a predetermined temperature, and then separating the different parts of the stock.

5. The herein described process of milling flour which consists in rinding the stock, cooling the ground stoclV to a temperature such that the vapor pressure of the moisture in the stock is less than the vapor pressure corresponding to the temperature of the air and apparatus with which the stock subse quently comes into contact, and maintaining a substantially uniform temperature and humidity of the surrounding atmosphere in the mill.v

Witness my hand, this 26th day of August, 916.

CHARLES WEBSTER ANDREWS. Witnesses:

` C. W. PARKER,

M. J. PrrrMAN. 

